1. Field of the Invention
The present invention relates to a probe station for testing a semiconductor wafer, and more particularly to a probe card locking device of a semiconductor wafer probe station for locking a probe card with a prescribed force.
2. Description of the Prior Art
Probing is one kind of a semiconductor analysis apparatus which includes a characteristics test of respective chips or the like upon a semiconductor wafer having passed through a predetermined unit process. The probing is performed by a device for testing the characteristics of a corresponding chip by setting up a probe on a transistor or pad of an IC chip. There is a known REL-5000 series probe station manufactured by Cascade Microtech, Inc. in the United States sold under the trademark of "alessi".
In the REL-5000 series probe station, the probe card is mounted to the pads of a transistor or IC chip placed onto a probe card holder, and an electron microscope having a objective stand on which the probe card is disposed is utilized to perform the test with respect to the characteristics of the corresponding chip, etc.
The probe card mounted to the probe card holder is formed of a small-sized substrate substantially shaped as a rectangle. An externally-connecting pad for connection to a tester and so forth is formed to one side of the substrate. A plurality of probes for transmitting/receiving signals by contacting the corresponding chip of the semiconductor wafer are arranged around the periphery of a thruhole formed in the center of the probe card.
The probe card is disposed on the semiconductor wafer placed on the probe card holder, in which the probes extend toward the center of the thruhole to correspondingly contact the pads of the chip on a one to one basis in order to communicate signals between the chip and tester, thereby performing the test. At this time, since the probes of the probe card must simultaneously contact the pads of the chip, to ensure exactness of the test, the accurate position setting of the probe card is very important.
For this operation, the probe card holder is provided to a head of the tester to accurately lock the probe card to its position.
This conventional probe card locking structure using the probe card holder as above will be described below.
The probe card holder includes locking members for downwardly pressing to lock opposite sides of the probe card. The locking members are attached/detached and moved upwardly and downwardly by means of a plurality of securing bolts. By releasing the bolts, the locking members are separated from a pair of frames of the holder (or the locking members are spaced apart from the frames of the holder by a predetermined distance). Then, the probe card is seated in a space formed between the frames of the holder. By screwing the bolts, the locking members press the probe card seated on the frames of the holder. Therefore, the probe card is fixed due to the pressing of the locking members, and the plurality of probes are thereby locked to make overall contact with the pads of the corresponding chip.
In the above-described probe card locking device, however, after the bolts are released to separate the locking members from the frames, a probe card is mounted to the space between two members. Then, the locking members are joined for being locked by screwing the bolts, which makes the locking operation troublesome. In addition, the coupling force exerted upon respective bolts as they are screwed down is different, causing displacement of the probe card toward any one direction when being locked, thereby causing a contact failure. Consequently, a lot of set-up time for correcting the displacement is required.
Moreover, the conventional probe card locking device in using bolts for carrying out the locking operation can be adversely affected in regard to usage or safety aspects of the system since the locking bolts can be inadvertently dropped on the probe card or semiconductor wafer to cause damage of the probe card, deterioration of the semiconductor wafer, etc.